Use streams from lightweight test

test/exception/insert_exception_tests.cpp

@@ -3,7 +3,6 @@
 // Distributed under the Boost Software License, Version 1.0. (See accompanying
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 #include "./containers.hpp"
-#include <iostream>
 
 #include "../helpers/helpers.hpp"
 #include "../helpers/invariants.hpp"